1. Field of the Invention
The present invention relates to an automotive alternator driven by an internal combustion engine and mounted to, for example, an automotive vehicle such as a passenger car or a truck, and in particular, relates to an automotive alternator which can realize high output and high efficiency and in which noise can be reduced.
2. Description of the Related Art
Generally, cooling ventilation is supplied to coil ends, which are heat producing portions, in order to realize compact high output in a dynamo-electric machine. Also, in order to suppress wind noise due to ventilation at this location, it is necessary to reduce the size of the coils ends which are a ventilation drag. Namely, it is necessary to improve the space, factor of electric conductors housed in the magnetic circuit of the stator and to line up and increase the density of bridge portions (bridge portions outside a stator core are called coil ends) of the stator winding.
Constructions aimed at increasing the space factor of the electrical conductors using short conductor segments for the electrical conductors in the stator and at lining up and increasing the density of the coil ends have been proposed in Japanese Patent Publication No. 2927288. However, since the stator winding taught in this publication is constructed from a plurality of short conductor segments, connecting welds are made. The existence of these welds limits the amount which the height of the coil ends may be reduced and is a source of interference.
On the other hand, Japanese Patent Laid-open No. Hei 11-164519 teaches shifting the height of the coil in the axial direction to increase the exposed surface area and thus improve the cooling performance of the coil end groups. However, with this construction, copper loss increases because the coil end height becomes larger, generated heat increases and the amount which the temperature may be lowered is limited even if the cooling performance is improved. Furthermore, since there is a large surface area exposed to cooling air flowing in a radial direction from a fan, the coil ends become a ventilation drag, pressure loss increases and noise worsens.
The present invention aims to solve the above problems with the conventional art and an object of the present invention is to provide an alternator which can realize high output and high efficiency and in which noise can be reduced.
According to one aspect of the present invention there is provided an automotive alternator including:
a rotor;
a stator including:
a stator core disposed facing the rotor; and
a polyphase stator winding installed in the stator core; and
a bracket housing and supporting the rotor and the stator;
the stator core formed with a number of slots extending axially at a predetermined pitch in a circumferential direction,
the polyphase stator winding including a number of winding portions in which long wire strands are wound so as to alternately occupy an inner layer and an outer layer in a slot depth direction within the slots at intervals of a predetermined number of slots, the wire strands folding back outside the slots at axial end surfaces of the stator core to form turn portions,
and
a plurality of the wire strands lining up in a row in a radial direction inside the slots of the stator core, the turn portions of the wire strands being roughly the same shape and aligning at roughly the same pitch in a circumferential direction to constitute coil end groups,
the coil end groups disposed in a plurality of rows in a radial direction,
a fan provided at an axial end portion of the rotor roughly facing the coil end group and generating cooling air flowing in a radial direction to ventilate the coil end group.
According to another aspect of the present invention there is provided an automotive alternator wherein: magnetic poles of the rotor are claw-shaped magnetic poles; the fan is provided at an axial end of the claw-shaped magnetic poles; shoulder portions of the claw-shaped magnetic poles are disposed facing the coil end groups; the fan faces a ventilation passage formed at a side of the coil ends away from the stator core.
According to yet another aspect of the present invention there is provided an automotive alternator wherein: cut-out portions of a rectilinear or curvilinear cross-sectional shape are provided in the shoulder portions of the claw-shaped magnetic poles, and an area of intersection between an outermost outer diameter surface of the rotor and a ridge line of the cut-out portions roughly coincides with an end surface of the stator core.
According to still another aspect of the present invention there is provided an automotive alternator wherein: cut-out portions of a rectilinear or curvilinear cross-sectional shape are provided in the shoulder portions of the claw-shaped magnetic poles, and an area of intersection between an axial end surface of the claw-shaped magnetic poles and a ridge line of the cut-out portions roughly coincides with an outer diameter of the fan.
According to yet another aspect of the present invention there is provided an automotive alternator wherein: cut-out portions of a rectilinear or curvilinear cross-sectional shape are provided in the shoulder portions of the claw-shaped magnetic poles, an area of intersection between an outermost outer diameter surface of the rotor and a ridge line of the cut-out portions roughly coincides with an end surface of the stator core, and an area of intersection between an axial end surface of the claw-shaped magnetic poles and a ridge line of the cut-out portions roughly coincides with an outer diameter of the fan.
According to still another aspect of the present invention there is provided an automotive alternator wherein: a fan is provided with blade surfaces thereof inclined toward a cut-out portion-side.
According to yet another aspect of the present invention there is provided an automotive alternator wherein: a portion inside the bracket facing the fan is a substantially empty space.
According to still another aspect of the present invention there is provided an automotive alternator wherein: planing means is provided at an inner circumferential portion of the coil end groups.
According to yet another aspect of the present invention there is provided an automotive alternator wherein: planing means is provided at an end portion of the coil end groups.
According to still another aspect of the present invention there is provided an automotive alternator wherein: planing means is provided at an inner circumferential portion and end portion of the coil end groups.
According to still yet another aspect of the present invention there is provided an automotive alternator wherein: a portion of the bracket facing the coil end group is a smooth surface and a ventilation passage for cooling air is formed between the smooth surface and a coil end group end portion.